The use of closure devices for fastening storage containers, including plastic bags, is generally well known. Furthermore, the manufacture of closure devices made of plastic materials is generally known to those skilled in the art, as demonstrated by the numerous patents in this area.
A particularly well-known use for closure devices is in connection with flexible storage containers, such as plastic bags. In some instances, the closure device and the associated container are formed from thermoplastic materials, and the closure device and the side walls of the container are integrally formed by extrusion as a single piece. Alternatively, the closure device and side walls of the container may be formed as separate pieces and then connected by heat sealing or any other suitable connecting process. In either event, such closure devices are particularly useful in providing a closure means for retaining matter within the bag.
Conventional closure devices typically utilize mating fastening strips or closure elements which are used to selectively seal the bag. With such closure devices, however, it is often difficult to determine whether the  fastening strips are fully occluded. This problem is particularly acute when the strips are relatively narrow. Accordingly, when such fastening strips are employed, there exists a reasonable likelihood that the closure device is at least partially open.
Such fastening strips devices are also particularly difficult to handle by individuals with limited manual dexterity. Thus, in order to assist these individuals and for ease of use by individuals with normal dexterity, the prior art has also provided sliders for use in opening and closing the fastening strips, as disclosed, for example, in U.S. Pat. Nos. 4,199,845, 5,007,142, 5,007,143, 5,010,627, 5,020,194, 5,070,583, 5,283,932, 5,301,394, 5,426,830, 5,431,760, 5,442,838, and 5,448,808. Some of these sliders include a separator which extends at least partially between the fastening strips. When the slider is moved in the appropriate direction, the separator divides the fastening strips and opens the bag.
During assembly of closure devices utilizing sliders, the sliders are often mounted onto fastening strips by moving the slider over the fastening strips in the vertical axis. Specifically, if the longitudinal axis of the fastening strips and slider is the X axis, the width is the transverse Y axis and the height is the vertical Z axis, the slider is attached to the fastening strips by moving the slider over the fastening strips in the vertical Z axis. In the past, sliders attached in the vertical Z axis have utilized either a multi-part design or folding design with the hinge along the X axis. In either case the slider must be properly positioned along the fastening strip while the slider components are either snapped or ultrasonically welded together. These procedures increase manufacturing costs. Examples of sliders with multiple parts are disclosed in U.S. Pat. Nos. 5,007,142 and 5,283,932 and folding plastic sliders  in U.S. Pat. Nos. 5,067,208, 5,070,583, and 5,448,808. Examples of single piece sliders which are inserted on unoccluded fastening strips are disclosed in U.S. Pat. Nos. 3,426,396, 3,713,923, 3,806,998 and 4,262,395.
The prior art has failed to afford a slider that is attached to the fastening strips in the vertical Z axis through a single step process. It would be desirable to have a slider that may be attached to the fastening strips in the vertical Z axis by merely urging the slider over the fastening strips. Such a device would reduce the manufacturing costs of closure devices utilizing sliders in addition to providing an effective and reliable means of attaching sliders to the fastening strips.